Lens with controlled backlight management

ABSTRACT

A lens for distribution of light predominantly toward a preferential side from a light emitter having an emitter axis and defining an emitter plane. The lens has an emitter-adjacent base end forming an emitter-receiving opening to an emitter-surrounding cavity defined by an inner surface which includes a front sector centered on the preferential side and a back sector centered on the non-preferential side radially opposite the preferential side. The front and back sectors differ in their respective configurations for refracting light from the emitter. The lens further includes an primary back surface positioned to receive light from at least a portion of the inner-surface back sector and configured for total internal reflection (TIR) thereof. The inner-surface back sector and the primary back surface extend along substantially elliptical cross-sections in planes substantially parallel to the emitter plane. The emitter-adjacent base end forms a back opening to a back cavity substantially centered on the non-preferential side and partially bounded by the primary back surface.

RELATED APPLICATIONS

This application is a continuation-in-part of currently pending U.S.application Ser. No. 12/173,721, filed on Jul. 15, 2008, which is basedin part on U.S. Provisional Application Ser. No. 61/055,958, filed May23, 2008.

FIELD OF THE INVENTION

This invention relates to lighting fixtures and, more particularly, toLED lightning fixtures for various common illumination purposes. Stillmore specifically, this invention relates to the field of lensing fordesired LED light distribution in LED lighting fixtures.

BACKGROUND OF THE INVENTION

In recent years, the use of light-emitting diodes (LEDs) for variouscommon lighting purposes has increased, and this trend has acceleratedas advances have been made in LEDs and in LED-array bearing devices,referred to as “LED modules.” Indeed, lighting needs which haveprimarily been served by fixtures using high-intensity discharge (HID)lamps, halogen lamps, compact florescent light and other light sourcesare now increasingly beginning to be served by LEDs. Creative workcontinues in the field of LED development, and also in the field ofeffectively utilizing as much of the light emitted from LEDs aspossible.

As is known, LED “packages,” which typically consist of a single LED (orsmall LED cluster) on a base with or without a “primary lens.” each havean individual lens thereover to direct light from the LED package asintended. (Such lens is sometimes referred to as a “secondary” lens whenthe package with which it is used includes a primary lens.) Developmentefforts have been made in the field of such lenses, with the intentionbeing to redirect some of the package-emitted light in a manner formingillumination patterns desired for particular applications. However, suchlenses have tended to fall short of the most desirable performance inthat some LED-emitted light is lost.

Typically, some of the light from LEDs is emitted at angles that causeLED-lighting fixtures to provide less than desirable and less than fullyefficient illumination patterns. Some prior lenses have been configuredto prevent undesirable light from exiting the lens and others to blocksuch light immediately upon its exiting the lens. Even though theseconfigurations were deemed necessary to achieve desired illuminationpatterns and to prevent so-called lighting “trespass,” they tended toresult in lost light and decreased efficiency of LED illuminators. Itwould be highly desirable to improve efficiency of the use of lightemitted by LEDs in lighting fixtures.

A typical LED emits light over a wide range of angles such that lightfrom the LED reaches a particular area of the output surface of the lensat somewhat different angles. This has made it very difficult to controlrefraction of such light. As a result, only a portion of light beingrefracted is refracted in a desired direction, while the reminder exitsthe lens with very little control. It would be desirable to provideimproved control of the direction of light exiting such lenses.

Trespass lighting can be evaluated by more than just the amount of lightemitted in an undesed direction; also to be considered is how far fromthe desired direction such light is directed. It would be highlybeneficial to provide a lighting apparatus which produces a desiredillumination pattern with a maximum amount of light emitted toward thespace intended to be illuminated, in typical commercial applications.

OBJECTS OF THE INVENTION

It is an object of the invention to provide improved LED lensing toovercome some of the problems and shortcomings of the prior art,including those referred to above.

Another object of the invention is to provide an LED lens with improvedlight-output efficiency for a variety of particular uses.

Another object of the invention is to provide an LED lens with improvedcontrol of the direction of light exiting the lens.

How these and other objects are accomplished will become apparent fromthe following descriptions and the drawings.

SUMMARY OF THE INVENTION

This invention is a lens with improved efficiency of distribution oflight predominantly toward a preferential side from a light emitter suchas an LED package having an emitter axis and defining an emitter plane.It is preferred that the light emitter is the LED package which is freeof a surrounding reflective surface. Such improved efficiency of lightoutput from the light emitter is achieved with the inventive lens whichis specifically designed for refraction and useful output of lightemitted in directions opposite to the desired illumination direction.The inventive lens directs the great majority of light from the emitterin the preferential-side direction, including light emitted at angleswhich previously resulted in the loss of such light. Such efficiency oflight use is provided without use of separate reflectors—that is, on alens-only basis.

The inventive lens has an emitter-adjacent base end which forms anemitter-receiving opening to an emitter-surrounding cavity defined by aninner surface. The inner surface includes a front sector centered on thepreferential side and a back sector centered on the non-preferentialside radially opposite the preferential side. The front sector has afirst configuration for refracting light from the emitter. The backsector has a second configuration for refracting light from the emitter.It is highly preferred that the second configuration differs from thefirst configuration. The lens also includes an axially-offset primaryback surface positioned to receive light from at least a portion of theinner-surface back sector and configured for total internal reflection(TIR) thereof. Light from the primary back surface is directed towardthe preferential side.

The term “toward,” as used herein with respect to direction of lightafter refraction or TIR, means that, after refraction or TIR such lightmoves closer to the indicated direction even if still diverging from theindicated direction. For example, “toward the preferential side” meansthat, if after refraction or TIR the light still moves in thenon-preferential direction, it does so at an angle closer (than prior tothe refraction or TIR) to the particular axial plane which distinguishesthe preferential side from the non-preferential side.

In highly preferred embodiments of the present invention, theinner-surface back sector and the primary back surface havesubstantially elliptical cross-sections in planes substantially parallelto the emitter plane.

The term “elliptical,” as used herein with respect to cross-sections ofa surface in planes substantially parallel to the emitter plane, meansthat such cross-sections are portions of ellipses. The term “wide side,”as used with respect to an ellipse, means a side which faces the majoraxis of the ellipse.

Referring to such elliptical cross-sections, it is preferred that eachcross-section be symmetrical about its midpoint, and that it be centeredon the plane extending from the center of the non-preferential side tothe center of the preferential side. In the preferred embodiments inwhich the elliptical cross-section face the ellipse major axis, thedistances from each elliptical cross-section to the emitter axisincrease at positions away from such s these cross-sections extend awayfrom the plane extending from the center of the non-preferential side tothe center of the preferential side. Such configuration allowswide-angle distribution of emitter light to the preferential side. Inother embodiments, in which the cross-sections of the inner-surface backsector and the primary back surface have shorter radii of curvature,narrower and farther patterns of light distribution toward thepreferential side are achieved.

The front sector preferably extends about the emitter axis along an arcthat is greater than the arc along which the back sector extends. Inpreferred embodiments of the inventive lens, the back-sector arc isabout half the front-sector arc. The lens of substantially bilaterallysymmetrical about a plane including the emitter axis.

In the inventive lens, the emitter-adjacent base end preferably forms aback opening to a back cavity substantially centered on thenon-preferential side and partially bounded by the primary back surface.The primary back surface transitions from near the inner-surface backsector at the emitter plane away from the emitter axis to terminate at aposition distal from the base end. It is preferred that the back cavityis further bounded by an axially-remote secondary back surface and anend surface. The incidental light that enters the back cavity ispreferably dispersed by the secondary back surface. The end surfaceextends from the primary back surface to the secondary back surface. Thesecondary back surface extends from the end surface to the base end andpreferably has substantially elliptical cross-sections in planesparallel to the emitter plane.

The inner-surface back sector preferably includes an intermediate backzone configured for refracting emitter light predominantly toward theprimary back surface for TIR thereof toward the preferential side.

In preferred embodiments, the inner-surface back sector also includes anaxially-adjacent back zone. The axially-adjacent back zone is configuredfor refracting emitter light away from the emitter plane and joins theintermediate back zone by transitioning from the emitter axis away fromthe emitter plane. The axially-adjacent back zone is preferablysubstantially cross-sectionally convex.

It is preferred that the intermediate back zone includes a firstintermediate back section extending away from the emitter axis. In suchembodiments, the intermediate back zone further preferably includessecond and third intermediate sections. The second intermediate backsection preferably extends from the first intermediate back section tothe axially-adjacent back zone. The third intermediate back sectionpreferably transitions from the first intermediate back section towardthe emitter plane and is configured for refracting emitter light towardthe emitter plane with progressively lesser refraction at positionsprogressively closer to the emitter plane. It is preferred that thesecond and third intermediate back sections extend substantiallyorthogonally to the emitter plane and have substantially ellipticalcross-sections in planes parallel to the emitter plane.

The term “toward the emitter plane” means that after being refracted thelight moves at smaller angles with respect to the emitter plane thanprior to the refraction. The term “away from the emitter plane” meansthat after being refracted the light moves at greater angles withrespect to the emitter plane than prior to the refraction.

The inventive lens further includes an outer surface configured forrefracting emitter light in predominantly off-axis directions toward thepreferential side. The outer surface has front and back output regions.The back output region is configured for refracting a preponderance oflight received from the inner-surface back sector and the primary backsurface toward the preferential side. The back output region is furtherconfigured for receiving at least a portion of light from the firstintermediate back surface and distributing it toward useful illuminationof the non-preferential side.

In preferred embodiments of this invention, the inner-surface frontsector includes a first, second and middle front regions. The firstfront region is adjacent to the emitter axis and is preferablyconfigured for refracting emitter light toward the emitter plane. Thesecond front region is spaced from the first front region and ispreferably configured for refracting emitter light away from the emitterplane. The middle front region joins and is substantiallycross-sectionally asymptotical to the first and second front regions. Itis preferred that the middle front region is positioned with respect tothe emitter to refract light toward the emitter plane by progressivelylesser amounts at positions progressively closer to the second frontregion.

In the preferred embodiments of the present invention, the front outputregion of the outer surface is configured for refracting light from theinner-surface front sector such that at the outer surface light fromeach front region is refracted substantially without overlapping lightfrom other front regions.

The second front region preferably terminates before reaching theemitter plane. The inner-surface front sector further preferablyincludes a base-adjacent front region which extends from the secondfront region and is configured such that the light emitted between thesecond front region and the emitter plane passes through thebase-adjacent front region substantially free of refraction.

The preferred embodiments of the inventive lens further include aperipheral front surface positioned to receive light from thebase-adjacent front region and configured for total internal reflection(TIR) thereof toward the outer surface. In such embodiments, theemitter-adjacent base end preferably forms a front opening to a frontcavity centered on the preferential side and partially bounded by theperipheral front surface.

As noted earlier, efficient use of LED light is important, particularlyin applications involving illumination toward a preferential side. Theinventive lens, in its preferred embodiments, is capable of directing10% more of the total emitted light toward the preferential side thanwith prior lenses designed for preferential-side distribution. In suchpreferred embodiments, the inventive lens effectively utilizes as muchas 90% of the emitter light for achieving useful illumination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged perspective view of the inventive lens.

FIG. 2 is an enlarged cross-sectional non-transparent perspective viewof the lens of FIG. 1 showing configurations of inner, back and frontcavities as well as the outer surface.

FIG. 3 is a greatly enlarged fragmentary cross-sectional perspectiveview of the lens of FIG. 1.

FIG. 4 is a greatly enlarged fragmentary cross-sectional side view ofthe lens of FIG. 1.

FIG. 5 is an enlarged top plan view of the lens of FIG. 1.

FIG. 6 is a greatly enlarged fragment of the top view of the lens ofFIG. 5.

FIGS. 7-9 are enlarged fragmentary cross-sectional perspective view ofthe lens of FIG. 1 showing cross-sections in planes substantiallyparallel to the emitter axis.

FIG. 10 is an enlarged cross-sectional front view of the lens of FIG. 1.

FIG. 11 is an enlarged back view of the lens of FIG. 1.

FIG. 12 is an enlarged cross-sectional side view of the lens of FIG. 1showing refraction of the emitter light.

FIG. 13 is an enlarged cross-sectional perspective view of the lens ofFIG. 12 showing refraction of the emitter light by the inner-cavity backsector and primary back surface.

FIG. 14 is an enlarged fragmentary cross-sectional side view of the lensof FIG. 12 showing distribution of the emitter light from theinner-cavity back sector and primary back surface.

FIG. 15 is a greatly enlarged fragmentary cross-sectional side view ofthe lens of FIG. 12 showing refraction of the emitter light by theinner-cavity front-sector regions and a peripheral front surface.

FIG. 16 is an enlarged fragmentary cross-sectional side view of the lensof FIG. 1 showing distribution of emitter light refracted as in FIG. 15by outer-surface front output region.

FIG. 17 is an enlarged fragmentary perspective top plan view of the lensof FIG. 1 showing distribution of the emitter light from theinner-cavity back sector and primary back surface.

FIG. 18 is an enlarged fragmentary perspective front top view of thelens of FIG. 1 showing distribution of the emitter light from theinner-cavity back sector and primary back surface.

FIG. 19 is an enlarged fragmentary perspective side view from above ofthe lens of FIG. 1 showing a fragmental light trace and an illuminationplot identifying position of this fragment of light thereon.

FIG. 20 is another enlarged fragmentary perspective side view from aboveof the lens of FIG. 1 showing a fragmental light trace and anillumination plot identifying position of this fragment of lightthereon.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1-20 illustrate lens 10 which is a preferred embodiment of theinvention. Lens 10 is for distribution of light predominantly toward apreferential side 5 from a light emitter 1 which has an emitter axis 2and defines an emitter plane 3. As seen at least in FIGS. 1 and 2, lightemitter 1 is an LED package which is free of a surrounding reflectivesurface.

Lens 10 has an emitter-adjacent base end 11 which forms anemitter-receiving opening 12 to an emitter-surrounding cavity 13 definedby an inner surface 14. Cavity 13 defines a space between emitter 1 andan inner-cavity surface 14 such that emitter light goes through air toenter lens material at inner-cavity surface 14. Because air and the lensmaterial, which may be acrylic or other suitable material, havedifferent refraction indexes, this results in bending of the light atinner-cavity surface 14.

Inner surface 14 includes a front sector 20 centered on preferentialside 5 and a back sector 30 centered on the non-preferential side 6which is radially opposite preferential side 5. As best seen in FIGS.1-5, front sector 20 has a first configuration for refracting light fromemitter 1. Back sector 30 has a second configuration for refractinglight from emitter 1. The second configuration differs from the firstconfiguration. Lens 10 also includes an axially-offset primary backsurface 15 positioned to receive light from at least a portion ofinner-surface back sector 30 and configured for total internalreflection (TIR) thereof. As illustrated in FIGS. 12-14, light fromprimary back surface 15 is directed toward preferential side 5.

FIGS. 1 and 5-9 show that inner-surface back sector 30 and primary backsurface 15 have substantially elliptical cross-sections in planessubstantially parallel to emitter plane 3. FIGS. 7-9 show cross-sectionsin planes parallel to emitter plane 3 at different distances fromemitter plane 3.

FIG. 6 further illustrates elliptical curvatures of inner-surface backsector 30 and primary back surface 15. FIG. 6 best shows how thesecross-sections extend from their respective points which are along aplane of lens symmetry 4 and are closest to emitter axis 2 away fromsymmetry plane 4 to positions which are farthest from emitter axis 2.

It is best shown in FIG. 5 that front sector 20 extends about emitteraxis 2 along an arc 24 and that the back sector extends along an arc 31.Front-sector arc 24 is greater than back-sector arc 31. FIG. 5 furthershows that back-sector arc 31 is about half front-sector arc 24. It canfurther be seen in FIG. 5 that lens 10 is bilaterally symmetrical aboutplane 4 which includes emitter axis 2.

As best seen in FIGS. 1-4, emitter-adjacent base end 11 further forms aback opening 40 to a back cavity 41 substantially centered onnon-preferential side 6 and partially bounded by primary back surface15. It can be seen that primary back surface 15 transitions from nearinner-surface back sector 30 at emitter plane 3 away from emitter axis 2to terminate at a position distal from base end 11. FIGS. 1-4 furtherillustrate that back cavity 41 is further bounded by an axially-remotesecondary back surface 42 and an end surface 43. End surface 43 extendsfrom primary back surface 15 to secondary back surface 42. Secondaryback surface 42 extends from end surface 43 to base end 11 substantiallyorthogonally to emitter plane 3 and, as best seen in FIGS. 3 and 6, hassubstantially elliptical cross-sections in planes parallel to emitterplane 3.

FIGS. 1-4 best show that the inner-surface back sector 30 includes anintermediate back zone 32 and an axially-adjacent back zone 33.Axially-adjacent back zone 33 joins intermediate back zone 32 bytransitioning from emitter axis 2 away from emitter plane 3. It is seenthat axially-adjacent back zone 33 is substantially cross-sectionallyconvex.

It is best seen in FIGS. 12-14 that intermediate back zone 32 isconfigured for refracting emitter light predominantly toward primaryback surface 15 for TIR thereof toward preferential side 5. FIGS. 12-14also show that axially-adjacent back zone 33 is configured forrefracting emitter light away from emitter plane 3.

As best shown in FIGS. 2-4, intermediate back zone 32 includes a firstintermediate back section 321 extending away from emitter axis 2, asecond intermediate section 322 and a third intermediate section 323.Second intermediate back section 322 extends from first intermediateback section 321 to axially-adjacent back zone 33. Third intermediateback section 323 transitions from first intermediate back section 321toward emitter plane 3. Second and third intermediate back sections 322and 323 extend substantially orthogonally to emitter plane 3. FIGS. 5-9illustrate that second and third intermediate back sections 322 and 323each have substantially elliptical cross-sections in planes parallel toemitter plane 3. As best seen in FIGS. 12-14, third intermediate backsection 323 is configured for refracting emitter light toward emitterplane 3 width progressively lesser refraction at positions progressivelycloser to emitter plane 3.

Inventive lens 10 further includes an outer surface 17 configured forrefracting emitter light in predominantly off-axis directions towardpreferential side 5. Outer surface 17 has front and back output regions18 and 19. Outer surface 17 extends for a majority of the 180° aboutemitter axis 2 to provide a large refractive output surface for awide-angle distribution of emitter light with improved control. FIG. 4best shows that outer surface 17 extends for about a 150° around emitteraxis 2.

FIGS. 12-14 illustrate that back output region 19 is configured forrefracting a preponderance of light received from inner-surface backsector 30 and primary back surface 15 toward preferential side 5. Backoutput region 19 is further configured for receiving at least a portionof light from first intermediate back surface 321 and distributing suchlight toward useful illumination of non-preferential side 6.

FIG. 16 shows outer-surface front output region 18 including anaxis-adjacent first output area 181, a second output area 182 spacedfrom axis-adjacent first output area 181, and a middle output area 183joining first and second output areas 181 and 182. Outer-surface frontoutput region 18 further includes a base-adjacent outer-surface area 184which extends from second output area 182 and is substantially free fromreceiving any emitter light. Base-adjacent outer-surface front area 184is substantially orthogonal to emitter plane 3. It should be appreciatedthat, since the base-adjacent outer-surface front area 184 substantiallydoes not participate in distribution of emitter light, it may have anyconfiguration dictated by positioning and mounting of lens 10 or otherfactors such as material or space conservation.

FIG. 15 shows that inner-surface front sector 20 includes a first,second and middle front regions 21, 22 and 23, respectively. First frontregion 21 is adjacent to emitter axis 2 and is configured for refractingemitter light which passes through axis-adjacent first region 21 towardthe emitter plane 3. This provides a broader distribution of the lightemitted about axis 2 and allows to enlarge the size of outer-surfacefirst output area 181 to achieve better refraction of light outside lens10. Light received by axis-adjacent first front region 21 has thehighest intensity because typically the highest illumination intensityof the emitter light is concentrated about axis 2. By refracting lighttoward emitter plane 3 (or away from axis 2), first front region 21allows for dispersion of such light over a larger space. This improvesuniformity of illumination intensity and substantially decreases aso-called “hot-spot” effect in a plot of illumination intensitydistribution. FIG. 15 further illustrates that axis-adjacent first innerregion 21 is substantially cross-sectionally concave.

Second front region 22 is spaced from first front region 21 and isconfigured for refracting emitter light away from emitter plane 3. It isseen in FIG. 15 that second inner region 22 is substantiallycross-sectionally convex. Second front region 22 moves light, whichmostly includes light emitted within about 30° from emitter plane 3,away from base-adjacent outer-surface front region 184. As can be seenin FIGS. 12, 13 and 17-20, base-adjacent outer-surface front area 184 issurrounded by structures 70 which may serve to secure lens 10 withrespect to emitter 1 or be a shield blocking emitter light from going inan undesirable direction. As a result, any light that would arrive atbase-adjacent front area 184 would be blocked by such structures 70 andwould be eventually lost. In prior lenses, because some of the light waslost, to meet goals of desired polar candela plots, the outer surfacehad to be designed to bend some of the axis-adjacent light to the sidesto provide required illumination. By refracting light received by secondfront region 22 away from emitter plane 3 (or toward emitter axis 2),this light is received by outer surface 17 at output area 182 which notonly transmits such light-out of lens 10 but also further refracts thislight in a desired direction, i.e., toward emitter plane 3 forillumination farther from emitter axis 2, as shown in FIG. 16.Therefore, since such light from second front region 22 transmitted bysecond output area 182 provides desired illumination at the sides ofdesired illumination patterns, there is no need for bending for suchpurpose axis-adjacent light transmitted by first output area 181.

In prior lenses, the space between the emitter and inner lens surfacewas filled with an optical gel such that the emitter light passedtherethrough without refraction and arrived to the outer surface at thesame angle as emitted. In such prior lenses, the outer surface was theonly vehicle for light refraction. When compared to such prior lenses,the configuration of front output region 18 of outer surface 17 of lens10 is unexpectedly substantially simpler then of those prior lenses. Inthe prior lenses, light arrived at the outer surface at broad range ofangles. Thus, almost all these angles had to be taken into account informing that prior outer surface for refraction of light in a desirabledirection. In lens 10, the direction of the majority of emitter light isinitially substantially controlled by inner surface 14 and light fromone of inner-surface front-sector regions is received substantially byonly a corresponding one front output area of outer surface 17. As aresult, each one front output area of outer surface 17 receives lightwhich arrives at substantially narrow sector of angles. This, coupledwith improved efficiency eliminating the need for bending axis-adjacentlight for side illumination, simplifies the configuration of the frontoutput region 18 of outer surface 17 for refraction of such light in adesired direction and, therefore, decreases a probability of anirregularity impact on the light-output direction.

Middle front region 23 joins and is substantially cross-sectionallyasymptotical to first and second front regions 21 and 22. Middle frontregion 23 is positioned with respect to emitter 1 to refract lighttoward emitter plane 3 by progressively lesser amounts at positionsprogressively closer to second front region 22. In some cases, middleregion 23 may be configured and positioned to allow emitter light topass therethrough with substantially no refraction. As best shown inFIG. 15, middle inner region 23 is substantially cross-sectionallylinear. In other words, middle inner region 23 is of substantiallytruncated conical shape.

FIG. 16 shows that front output region 18 of outer surface 17 isconfigured for refracting light from inner-surface front sector 20 suchthat at outer surface 17 light from each of inner-surface front regions21, 22 and 23 is refracted substantially without overlapping light fromother inner-surface front regions. Each of output regions 181, 182 and183 is configured for refracting the light from a corresponding one orinner-surface front regions 21, 22 and 23. As best seen in FIG. 16,axis-adjacent first output area 181 is configured for receiving emitterlight from axis-adjacent inner-surface first front region 21 and furtherrefracting such light toward emitter plane 3. Second output area 182 isconfigured for receiving emitter light from inner-surface second frontregion 22 and refracting such light substantially toward emitter plane3. Middle output area 183 is configured for receiving emitter light frominner-surface middle front region 23 and refracting a majority of suchlight substantially toward emitter plane 3.

FIGS. 1, 2 and 10-12 best show a flange 71 that surrounds lens 10substantially along emitter plane 3 and extends between base adjacentend 11 and outer surface 17. The illustrated embodiment shows lens 10 ofthe type that can be oriented for desired light distribution of eachindividual emitter 1. This allows for each of a plurality of lenses 10positioned over emitters on an LED-array module be differently orientedto achieve desired illumination distribution from such LED-array moduleas a whole. In such embodiment, flange 71 serves for securing lens 10about emitter 1 by sandwiching flange 71 between a printed circuit boardand other structures 70 such as sealing gasket or an LED-array modulecover. It should be understood that this is just an exemplaryconfiguration of lens 10. Outer surface 17 can have other configurationswhich would be dictated by an intended illumination pattern.Alternatively, lens 10 can be a part of a larger unit for positioningover a plurality of emitters and incorporating a plurality of lenseslike lens 10 or of different configurations.

It is further seen in FIG. 15 that second front region 22 terminatesbefore reaching emitter plane 3. Inner-surface front sector 20 furtherincludes a base-adjacent front region 25 which extends from second frontregion 22 and is configured such that the light emitted between secondfront region 22 and emitter plane 3 passes through base-adjacent frontregion 25 substantially free of refraction.

Inventive lens 10 further includes a peripheral front surface 16positioned to receive light from base-adjacent front region 25 andconfigured for total internal reflection (TIR) thereof toward outersurface 17. As best seen in FIG. 3, emitter-adjacent base end 11 forms afront opening 50 to a front cavity 51 centered on preferential side 5and partially bounded by peripheral front surface 16.

FIGS. 5 and 6 show inner-surface front sector 20 of substantiallycircular annular cross-sections in planes substantially parallel toemitter plane 3. Alternatively, inner-surface front sector 20 andperipheral front surface can have shapes that result in substantiallyoval or ovoid cross-sections made in planes substantially parallel toemitter plane 3. In other words, these surfaces may have symmetriesother than rotational. It should be further appreciated that, dependingon the intended illumination pattern, the inventive lens may be shapedwithout a symmetry and have asymmetrical surfaces.

While the principles of the invention have been shown and described inconnection with specific embodiments, it is to be understood that suchembodiments are by way of example and are not limiting.

1. A lens for distribution of light predominantly toward a preferentialside from a light emitter having an emitter axis and defining an emitterplane, comprising: an outer surface configured for refracting emitterlight; an emitter-adjacent base end forming an emitter-receiving openingto an emitter-surrounding cavity; a refracting inner surface definingthe emitter-surrounding cavity and including: a front sector centered onthe preferential side and having a first configuration for refractinglight from the emitter; and a back sector centered on thenon-preferential side radially opposite the preferential side and havinga second configuration for refracting light from the emitter, the secondconfiguration differing from the first configuration; and anaxially-offset reflecting primary back surface positioned to receivelight from at least a portion of the refracting-inner-surface backsector and configured for total internal reflection (TIR) thereof towardthe lens outer surface.
 2. The lens of claim 1 wherein light from theprimary back surface is directed toward the preferential side.
 3. Thelens of claim 1 wherein the inner-surface back sector and the primaryback surface having substantially elliptical cross-sections in planessubstantially parallel to the emitter plane.
 4. The lens of claim 3wherein such substantially-elliptical cross-sections are elliptical widesides.
 5. The lens of claim 1 wherein the emitter-adjacent base endforms a back opening to a back cavity substantially centered on thenon-preferential side and partially bounded by the primary back surface.6. The lens of claim 5 wherein the primary back surface transitions fromnear the inner-surface back sector at the emitter plane away from theemitter axis to terminate at a position distal from the base end.
 7. Thelens of claim 6 wherein the back cavity is further bounded by anaxially-remote secondary back surface and an end surface extending fromthe primary back surface to the secondary back surface, the secondaryback surface extending from the end surface to the base end and havingsubstantially elliptical cross-sections in planes parallel to theemitter plane.
 8. The lens of claim 1 wherein the inner-surface backsector includes an intermediate back zone configured for refractingemitter light predominantly toward the primary back surface for TIRthereof toward the preferential side.
 9. The lens of claim 8 wherein theinner-surface back sector further includes an axially-adjacent back zonewhich is configured for refracting emitter light away from the emitterplane and joins the intermediate back zone by transitioning from theemitter axis away from the emitter plane.
 10. The lens of claim 9wherein the axially-adjacent back zone is substantiallycross-sectionally convex.
 11. The lens of claim 9 wherein theintermediate back zone includes a first intermediate back sectionextending away from the emitter axis.
 12. The lens of claim 11 whereinthe intermediate back zone further includes: a second intermediate backsection which extends from the first intermediate back section to theaxially-adjacent back zone; and a third intermediate back sectiontransitioning from the first intermediate back section toward theemitter plane and configured for refracting emitter light toward theemitter plane with progressively lesser refraction at positionsprogressively closer to the emitter plane.
 13. The lens of claim 12wherein the second and third intermediate back sections extendsubstantially orthogonally to the emitter plane and having substantiallyelliptical cross-sections in planes parallel to the emitter plane. 14.The lens of claim 1 wherein the outer surface is configured forrefracting emitter light in predominantly off-axis directions toward thepreferential side.
 15. The lens of claim 14 wherein the outer surfacehas front and back output regions, the back output region beingconfigured for refracting a preponderance of light received from theinner-surface back sector and the primary back surface toward thepreferential side.
 16. The lens of claim 15 wherein the inner-surfacefront sector includes: a first front region adjacent to the emitter axisand configured for refracting emitter light toward the emitter plane; asecond front region spaced from the first front region and configuredfor refracting emitter light away from the emitter plane; and a middlefront region joining and substantially cross-sectionally asymptotical tothe first and second front regions, the middle front region beingpositioned with respect to the emitter to refract light toward theemitter plane by progressively lesser amounts at positions progressivelycloser to the second front region.
 17. The lens of claim 16 wherein thefront output region of the outer surface is configured for refractinglight from the inner-surface front sector such that at the outer surfacelight from each front region is refracted substantially withoutoverlapping light from other front regions.
 18. The lens of claim 1wherein the front sector extends about the emitter axis along an arcthat is greater than the arc along which the back sector extends. 19.The lens of claim 18 wherein the back-sector arc is about half thefront-sector arc.
 20. The lens of claim 1 being substantiallybilaterally symmetrical about a plane including the emitter axis. 21.The lens of claim 1 wherein the back sector of the refracting innersurface includes at least a pair of surface portions transverse to eachother.
 22. The lens of claim 1 wherein the front sector of therefracting inner surface has a substantially smooth surfaceconfiguration extending to the juncture of the front and back sectors.23. The lens of claim 22 wherein the back sector of the refracting innersurface includes at least a pair of surface portions transverse to eachother.
 24. A lens for distribution of light predominantly toward apreferential side from a light emitter having an emitter axis anddefining an emitter plane, comprising: an emitter-adjacent base endforming an emitter-receiving opening to an emitter-surrounding cavity;an inner surface defining the emitter-surrounding cavity and including(a) a front sector centered on the preferential side and having a firstconfiguration for refracting light from the emitter and (b) a backsector centered on the non-preferential side radially opposite thepreferential side and having a second configuration for refracting lightfrom the emitter, the second configuration differing from the firstconfiguration, the inner-surface front sector including: a first frontregion adjacent to the emitter axis and configured for refractingemitter light toward the emitter plane; a second front region spacedfrom the first front region and configured for refracting emitter lightaway from the emitter plane, the second front region terminating beforereaching the emitter plane; a base-adjacent front region extending fromthe second front region and being configured such that the light emittedbetween the second front region and the emitter plane passes through thebase-adjacent front region substantially free of refraction; and amiddle front region joining and substantially cross-sectionallyasymptotical to the first and second front regions, the middle frontregion being positioned with respect to the emitter to refract lighttoward the emitter plane by progressively lesser amounts at positionsprogressively closer to the second front region; and an axially-offsetprimary back surface positioned to receive light from at least a portionof the inner-surface back sector and configured for total internalreflection (TIR) thereof.
 25. The lens of claim 24 further includes aperipheral front surface positioned to receive light from thebase-adjacent front region and configured for total internal reflection(TIR) thereof toward a lens outer surface.
 26. The lens of claim 25wherein the emitter-adjacent base end forms a front opening to a frontcavity centered on the preferential side and partially bounded by theperipheral front surface.
 27. A lens for distribution of lightpredominantly toward a preferential side from a light emitter having anemitter axis and defining an emitter plane, comprising: an outer surfaceconfigured for refracting emitter light; an emitter-adjacent base endforming an emitter-receiving opening to an emitter-surrounding cavity; arefracting inner surface which defines the emitter-surrounding cavityand is configured for refracting light from the emitter, the refractinginner surface including: a front sector centered on the preferentialside; and a back sector centered on the non-preferential side radiallyopposite the preferential side and having a surface configurationdiffering from a front-sector surface configuration; and a back openingto a back cavity partially bounded by a reflecting primary back surfacepositioned to receive light from at least a portion of therefracting-inner-surface back sector and configured for total internalreflection (TIR) thereof toward the lens outer surface.
 28. The lens ofclaim 27 wherein the emitter-adjacent base end forms a front opening toa front cavity partially bound by a peripheral front surface positionedto receive light from a base-adjacent region of the inner-surface frontsector and configured for total internal reflection (TIR) thereof towardthe lens outer-surface.
 29. A lens for distribution of lightpredominantly toward a preferential side from a light emitter having anemitter axis and defining an emitter plane, comprising: an outer surfaceconfigured for refracting emitter light; an emitter-adjacent base endforming an emitter-receiving opening to an emitter-surrounding cavity; arefracting inner surface which defines the emitter-surrounding cavityand is configured for refracting light from the emitter, the refractinginner surface including: a front sector centered on the preferentialside; and a back sector centered on the non-preferential side radiallyopposite the preferential side and having substantially ellipticalcross-sections in planes substantially parallel to the emitter plane, aback-sector surface configuration differing from a front-sector surfaceconfiguration; and a reflecting primary back surface positioned toreceive light from at least a portion of the refracting-inner-surfaceback sector and configured for total internal reflection (TIR) thereoftoward the lens outer surface, the reflecting primary back surfacehaving substantially elliptical cross-sections in planes substantiallyparallel to the emitter plane.